The tail fin configuration in projectiles is an important aspect in determining projectile performance. One known tail fin configuration includes fins that cause the projectile to spin during flight. One of the drawbacks with projectiles that include this type of fin configuration is that the projectiles have limited maneuverability rendering them inadequate from many applications.
Another known tail fin configuration for projectiles is a scissors-type tail fin that allows the projectile to perform well but can be quite costly. The cost associated with scissors-type tail fins has lead to the development of projectiles that include wrap-around tail fins.
There are some inherent design constraints that are associated with configuring projectiles to include wrap-around tail fins. These design constraints are even more problematic than the usual design constraints because projectiles with wrap-around tail fins have not previously been used in conjunction with muzzle brakes, and many of the cannons that are used to launch projectiles are now using some form of muzzle brake.
Muzzle brakes are now typically included in cannons that are used to launch projectiles because muzzle brakes reduce recoil within a cannon by capturing and deflecting gas which is generated during projectile launch from the cannon. When a cannon with a muzzle brake is used to launch a projectile that includes wrap-around tail fins, the wrap-around tail fins must delay opening until the tail fins have exited the cannon. The wrap-around tail fins are usually configured to open as soon as possible after exiting the cannon.
One of the drawbacks that is associated with using a wrap-around tail fin configuration on projectiles that are launched from cannons which include muzzle brakes is that the wrap-around tail fins undesirably trap gas as the projectile is launched from the cannon. This gas trapping within the wrap-around tail fins can cause unwanted damage to the projectile and/or the cannon that launches the projectile. In addition, the unwanted trapping of gases by the wrap-around tail fins during launch of the projectile may adversely affect the initial operation of the projectile.
The drawbacks that are associated with gas trapping can be overcome by including openings in the wrap-around tails fins. The openings allow gas that is expelled by the projectile during launch to pass through the openings in order to relieve pressure. However, the addition of such openings in the fins causes unwanted drag on the fins once the fins are deployed during flight.